Double stitch sewing machines



W. ENGEL DOUBLE STITCH SEWING MACHINES Feb. 21, 1961 s Sheets-Sheet 1 Filed Oct. 24, 1956 Feb. 21, 1961 w. ENGEL 2,972,320

DOUBLE STITCH SEWING MACHINES Feb. 21, 1961 w. ENGEL 2,972,320

DOUBLE STITCH SEWING MACHINES Filed Oct. 24, 1956 3 Sheets-Sheet 3 DOUBLE STITCH SEWING MACHINES Wolfgang Engel, Bielefeld, Germany, assignoito Phoenix Naehmaschinen A.-G. Baer 8: Rempel, Bielefeld, Germany Filed Oct. 24, 1956, Ser. No. 618,036

Claims priority, application Germany Nov. 2, 1955 2 Claims. (Cl. 112-215) and which has a toothed head or dog having a surface for attachment to the feeder bar which is arranged laterally of and parallel to the looper shaft, torsional moments occur in the feeder bar and sagging in the dog, due to the relatively great distance between the point of effectiveness of the force of the presser foot upon the dog and the attachement surface of the dog. As a result the two rows of teeth of the toothed head are no longer parallel to the stitch plate but the inner row of teeth projects higher above the stitch plate than the outer r'ow. As a consequence the machine no longer feeds the material straight, but the material deviates.

It is an object of the invention to eliminate these shortcomings even in very high speed double stitch sewing machines.

It is a further object of the invention to avoid the torsional moments of the feeder bar caused by the presser foot and the sagging in the dog.

Accordingly, the invention is incorporated in a machine which has a base in the form of a pan where the gear housing of the looper which has its plane of rotation disposed transversely of the direction of material feeding is provided at the bottom of the'pan which is open at the top, and above this driving gear housing the material feed dog is mounted which is secured to two carrier arms disposed on two sides of the looper shaft and which are connected with each other by means of transverse struts.

This arrangement of the material feed dog provides for an entirely torsion free mounting of the material feed dog which is only possible by virtue of the driving gear housing component being accommodated at the bottom of the pan, i.e. below the material feeder.

A particularly advantageous arrangement can be obtained if'the point of support for the fork of one carrier arm is arranged uponthe raising device in a manner that, as viewedfrom the top, theaxis of the joint of thepresser foot is crossed by an imaginary line connecting the point of support of one carrier arm with the outwardly located point of connection of the other carrier arm to the feeder pivot lever, in the region of the dog. This arrangement provides for particularly favorable absorption of forces by the material feeder or dog.

It is noted that double stitch sewing machines are known which are provided with a carrier arm which is projected beyond the dog and which engages at raising device with bifurcated means. The present invention takes advantage of this known means in order to obtain. the

absorption of forces which eliminates the torsional effects on the material feeding dog.

Further objects and details of the invention will become apparent from the embodiment illustrated in the drawing where:

Fig. 1 is a top perspective view of the base pan with the structural components with parts broken away,

Fig. 2 is a perspective view of the complete machine,

Fig. 3 is a partial top view of the base pan in dotted lines and of the structural components, and

Fig. 4 is an end view of the illustration in accordance with Fig. 1 taken in the direction of the arrows.

The outer walls 2 of the base pan not only enclose the driving means of the looper and of the toothed head or dog but also the looper, the toothed head 31 and the drive gear 4 on the shaft 5. The standard 6 of the arm 7 rests upon a base plate 8 which is connected to the upper edge of the pan along three walls of the periphery. The fourth edge of this plate 8 is supported on a rib 9 which extends transversely of the pan and is connected to the bottom of the pan. Beneath this plate 8 an aperture 11 is defined in the bottom 10 of the pan, corresponding in size substantially to the size of this plate, to permit mounting the drive gear 4 of the looper drive shaft 5.

A second substantially rectangular aperture 12 is located in the bottom 10 of the pan beneath the looper 1. The longitudinal sides of this aperture 12 extend in the direction of the axis of the looper. One of the short sides of the rectangular aperture 12 is defined by the wall 13 of the looper gear housing 14 which is mounted on bottom 10 of the pan. The other short side of aperture 12 which is located on the servicing or operating side of the machine is defined by the wall 2 of the pan. The outwardly located longitudinal side of aperture 12 is likewise defined by wall 2 of the pan while the inwardly disposed longitudinal side of the aperture 12 is defined by a rib 15 which extends at the same height as the pan from the wall 2 facing the operators side to the wall of the looper gear housing 13 To permit easier manipulation of the looper through aperture 12 in the pan bottom 10 the wall 2 which faces the operators side does not extend to the bottom 10 in the vicinity of aperture 12. I

An upwardly extending lever 27 is provided upon feeding or advancing shaft 26 on each side of the looper gear housing 14 at the ends of which the two carrier arms 28 are pivotally mounted extending parallel on both sides of the looper shaft 29. Arms 28 are connected by means of transverse bars 30, 30a for strengthening the carrier arm arrangement. At the rearward end arms 28 are secured by means of screws 28 to link bolt 27' which is connected to the upper ends of levers 27 The transverse bar 34} which faces the looper servessimultaneously as a supporting surface for the toothed head or dog 31'. The inner carrier arrn 28 is extended beyond the supporting surface and is provided at its end with the fork 32. The carrier arm rests with the jaws of fork 32 against the cross head 33 of the lifting lever 34 which is journalled in the pan. The pivot point 33 is provided at such a distance from the two connection points of the carrier arms with the lever 27, that as viewed from the top, a plane through the axis of pivot joint 39 of the presser foot crosses, in the area of the dog, the imaginary connecting line from pivot point 33 through pressure point 38 on dog 31 (Fig. 3) to the externally located pivot point 33a of the other carrier arm on lever 27. In this manner the pressure of the presser foot applies merely a small moment of rotation upon the carrier arm and the torsion load remains small. In order to keep the bending moments which are caused by the pressure of the presser foot against the dog small, the two carrier arms are brought forward beyond the attachment plane of the transverse bar 30 to the vertical plane of the engagement point of the presser force upon the dog, i.e. to the joint of the presser foot.

The horizontal and vertical movements of the feed dog 31 may be effected substantially in the manner set forth in applicants Patent No. 2,846,966 from the main Patented Feb. 21, 1951 or lopper drive shaft.

The feed shaft 26 may thus be linked to looper drive shaft for horizontal rocking movement by a cam and connecting link arrangement substantially as illustrated in the aforesaid patent. Bell crank lever 34 is linked by way of a connecting rod 34a, linked to a cam on shaft 5, which is indicated in dotted lines in Fig. 4. The horizontal movement of the connecting rod 34a is translated by lever 34 into up and down movement of the fork 32 and thereby provides the vertical movement of the dog 31.

The upper edge of the wall of the pan 2 is stiffened by a peripheral border 16. This border 16 is widened in the region of the stitch plate 17 in such a manner that it can serve to support stitch plate 17. The bearing block for the looper shaft which faces the looper carries a lug 22 which projects between the two carrier arms and upon which the stitch plate 17 rests. The entire pan is closed on top by a cover 23, which serves as a carrier plate for the material. The cover 23 is connected with the pan by means of several screws 24.

A conical rubber disk 35 is provided between screw head 24 and cover 23 for the purpose of tightening and noise suppression, and a rubber ring 36 is provided which extends circumferentially of the upper edge of the pan between the cover 23 and the pan. The cover 23 encompasses the stitch plate 17 and slide 25 as well as standard 6 from three sides. A rubber strip for sealing purposes is glued below the cover 23 circumferentially of the recess for the stitch plate 17. The cut out portion for the standard 6 is provided for the same reason with a rubber bead 37 which rests with its back against the standard 6.

I claim:

1. Double stitch sewing machine of the type comprising a base pan having walls at one end thereof defining a driving gear housing in the bottom of said base pan, a main shaft extending longitudinally of and journalled in said base pan, a looper having a looper shaft operatively connected to and extending with its axis transversely of said main shaft and disposed in said driving gear housing, a dog for feeding material disposed above 'said looper and a presser foot disposed above said dog,

said looper being disposed with its plane of rotation extending transversely of the direction of operation of said dog, an inner and an outer carrier arm each journalled at one end on a vertical link mounted on a feeding shaft, said feeding shaft being disposed along the rear wall of said pan and extending substantially parallel to said main shaft and being operatively connected thereto, said arms extending on both sides of said looper shaft transversely of said main shaft and projecting above said driving gear housing and supporting said dog symmetrically there: between above said driving gear housing, transverse bars connecting said inner and said outer carrier arms with one another, said presser foot being mounted for rock-' ing movement about a pivot axis and a portion of one of said carrier arms projecting forwardly of said looper and said dog, a lifting lever pivotally mounted in said driving gear housing having one arm operatively connectedto said drive shaft and presenting a cross head extending transversely of said forwardly projecting portion and said forwardly projecting portion having a bifurcated end in operative engagement with said cross head; a point of engagement of said bifurcated end with said cross head, a pressure point on said dog and a point on the journalled end of said other arm being generally disposed in a diagonal plane crossing said pivot axis of said presser foot at a point vertically above said dog.

2. Double stitch sewing machine of the type comprising a base pan having walls at one end thereof defining a driving gear housing in the bottom of said base pan, a main shaft extending longitudinally of and journalled in said base pan, a looper having a looper shaft operatively connected to and extending with its axis transversely of said main shaft and disposed in said driving gear housing, a dog for feeding material disposed above said looper and a presser foot disposed above said dog, said looper being disposed with its plane of rotation extending transversely of the direction of operation of said dog, an inner and an outer carrier arm each journalled at one end on a vertical link mounted on a feeding shaft, said feeding shaft being disposed along the rear wall of said pan and extending substantially parallel to said main shaft and being operatively connected thereto, said arms extending on both sides of said looper shaft transversely of said main shaft and projecting above said driving gear housing and supporting said dog symmetrically therebetween above said driving gear housing, transverse bars connecting said inner and said outer carrier arms with one another, said presser foot being mounted for rocking movement about a pivot axis and a portion of one of said carrier arms projecting forwardly of said looper and said dog, a lifting lever pivotally mounted in said driving gear housing having one arm operatively connected to said drive shaft and presenting a cross head extending transversely of said forwardly projecting portion and said forwardly projecting portion having a bifurcated end in operative engagement with said cross head; a point of engagement of said bifurcated end with said cross head, a pressure point on said dog and a point on the journalled end of said other arm being generally disposed in a diagonal plane crossing said pivot axis of said presser foot at a point vertically above said dog, each of said carrier arms for supporting said dog extending beyond the plane of rotation of the looper in a manner that said arms support the toothed head of said dog on both sides of the point of application of force by the presser foot on said feed dog.

References Cited in the file of this patent UNITED STATES PATENTS 326,821 Whitehill Sept. 22, 1885 355,735 Wardell Jan. 11, 1887 1,592,284 Meritt July 13, 1926 1,855,175 Braudes Apr. 26, 1932 2,333,438 Parry Nov. 2, 1943 2,350,807 Parry June 6, 1944 2,435,937 Clayton Feb. 10, 1948 2,848,964 Van Ness Aug. 26, 1958 

